CVE-2021-37746: textview_uri_security_check in textview.c in Claws Mail before 3.18.0, and Sylpheed through 3.7.0, does not ha

Q: How do I fix CVE-2021-37746?

claws-mail: upgrade to 3.18.0; sylpheed: upgrade to newer than 3.7.0; fedora: mitigate or apply the listed mitigation. Exact commands for each OS are on this page.

Q: Is CVE-2021-37746 being exploited?

CVE-2021-37746 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

Q: What does CVE-2021-37746 affect?

CVE-2021-37746 affects claws-mail, sylpheed, fedora. Severity is medium (CVSS 6.1). textview_uri_security_check in textview.c in Claws Mail before 3.18.0, and Sylpheed through 3.7.0, does not have sufficient link checks before accepting a click.

Q: How urgent is CVE-2021-37746?

Priority 43/100. On your watchlist

This month

MEDIUM 6.1WATCHLISTUPGRADEUPGRADEMITIGATE

CVE-2021-37746 is a medium-severity flaw (CVSS 6.1) affecting claws-mail, sylpheed, fedora. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

textview_uri_security_check in textview.c in Claws Mail before 3.18.0, and Sylpheed through 3.7.0, does not have sufficient link checks before accepting a click.

Why this priority

On your watchlist

A fixed release or distro patch exists.

Risk facts

CVSS score	6.1 (Medium)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	Required
EPSS exploit chance	1.2% (top 33%)
CISA exploited list	No
Weakness	CWE-601
Published	2021-07-30
Last modified	2026-06-17

Publisher (CNA): MITRE · Vendor: claws-mail · fedoraproject · sylpheed project

Last updated 2026-06-17 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2021-07-30 15:15 UTCPublished CVE record published
2026-06-17 04:01 UTCUpdated Record last modified

claws-mail claws-mail UPGRADE

Affected: < 3.18.0

Fixed in: 3.18.0

Safe to downgrade to: no unaffected older release

1. Check installed version

apt-cache policy claws-mail || rpm -q claws-mail || claws-mail --version

2. UPGRADE to 3.18.0 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade claws-mail

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade claws-mail

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

sylpheed project sylpheed UPGRADE

Affected: <= 3.7.0

Fixed in: newer than 3.7.0

Safe to downgrade to: no unaffected older release

1. Check installed version

apt-cache policy sylpheed || rpm -q sylpheed || sylpheed --version

2. UPGRADE to newer than 3.7.0 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade sylpheed

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade sylpheed

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

fedoraproject fedora MITIGATE

Affected: 33 · 34

Fixed in: no fixed release known

Safe to downgrade to: a release before 33

Check your OS release

cat /etc/os-release; uname -r

Debian / Ubuntu

sudo apt update && sudo apt full-upgrade

RHEL / Amazon Linux / Fedora

sudo dnf upgrade --refresh

Windows

Install the latest cumulative update from Windows Update

If no patch exists yet

OS downgrades are not safe. Apply the vendor mitigation from the advisory and restrict exposure.

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2021-37746?

claws-mail: upgrade to 3.18.0; sylpheed: upgrade to newer than 3.7.0; fedora: mitigate or apply the listed mitigation. Exact commands for each OS are on this page.

Is CVE-2021-37746 being exploited?

CVE-2021-37746 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2021-37746 affect?

CVE-2021-37746 affects claws-mail, sylpheed, fedora. Severity is medium (CVSS 6.1). textview_uri_security_check in textview.c in Claws Mail before 3.18.0, and Sylpheed through 3.7.0, does not have sufficient link checks before accepting a click.

How urgent is CVE-2021-37746?

Priority 43/100. On your watchlist

Related CVEs

CVE-2020-16094 HIGH 7.5 UPGRADE MITIGATE In imap_scan_tree_recursive in Claws Mail through 3.17.6, a malicious IMAP server can trigger stack consumptio
CVE-2020-15917 CRITICAL 9.8 UPGRADE MITIGATE common/session.c in Claws Mail before 3.17.6 has a protocol violation because suffix data after STARTTLS is mi
CVE-2015-8708 HIGH 7.3 DOWNGRADE Stack-based buffer overflow in the conv_euctojis function in codeconv.c in Claws Mail 3.13.1 allows remote att
CVE-2015-8614 HIGH 7.3 UPGRADE MITIGATE Multiple stack-based buffer overflows in the (1) conv_jistoeuc, (2) conv_euctojis, and (3) conv_sjistoeuc func
CVE-2014-2576 MEDIUM 6.8 UPGRADE MITIGATE plugins/rssyl/feed.c in Claws Mail before 3.10.0 disables the CURLOPT_SSL_VERIFYHOST check for CN or SAN host

References

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